Self aligning stuffing box

ABSTRACT

In a combination of an oil well pumping unit with sucker rods and the like, a self aligning stuffing box and well head seal to accommodate misalignment of the rods and tubing. The self aligning stuffing box structure includes a body member on a well tubing and a rod guide member mounted on the body member for limited universal movement. A guide extension is on the rod guide member and has a bore and an enlarged chamber. A rod extends through the guide extension bore and chamber, guide member, and body member into the oil well. Packing or seals in the guide extension sealingly engages the rod above and below the chamber to provide operative seals. Pressure sensitive members communicate with the guide member below the packing or seals therein to indicate fluid pressure in the chamber. Liquid pressure responsive structure communicates with the chamber and provides a signal in the event liquid accumulates in the chamber above a predetermined pressure; as by flowing through the packing or seals below the chamber.

[ June 3, 1975 United States Patent [1 1 Renfrow SELF ALIGNING STUFFING BOX [57] ABSTRACT In a combination of an oil well pumping unit with sucker rods and the like, a self aligning stuffing box and well head seal to accommodate misalignment of the rods and tubing. The self aligning stufi'mg box structure includes a body member on a well tubing Inventor: William Neil Renfrow, 3306 58 St.,

Lubbock, Tex. 79408 Oct. 9, 1973 [22] Filed:

[21] Appl. No.: 404,768

and a rod guide member mounted on the body member for limited universal movement. A guide extension is on the rod guide member and has a bore and an enlarged chamber. A rod extends through the guide extension bore and chamber, guide member, and body i 30.4 3 l 1 /S W31 ,3 0. 00 4 04 1 -1 W .O 6 32 7 a 7 2 W72 7 B "2 7 u. 7 mm 2 "a mh "C n r n "a "Q n S a m 5 mm U IF 1 .ll 2 8 5 55 member into the oil well. Packing or seals in the guide extension sealingly engages the rod above and below [56] References Cited UNITED STATES PATENTS the chamber to provide operative seals. Pressure sensitive members communicate. with the guide member 277/2 below the packing or seals therein to indicate fluid pressure in the chamber. Liquid pressure responsive structure communicates with the chamber and provides a signal in the event liquid accumulates in the 277/2 chamber above a predetermined pressure; as by flow- 865 874 Culbertson...

996 Barnett 830 Orr et al.

927 Faccou 925 Mattoon ing through the packing or seals below the chamber.

Primary ExaminerSamuel B. Rothberg 5 Claims, 5 Drawing Figures Attorney, Agent, or FirmFishburn, Gold & Litman an u a r .avl p 4 III. I

Iii:

SELF ALlGNlNG STUFFING BOX The present invention relates to oil well pump heads and more particularly to a device for accommodating misalignment of oil well rods with a stuffing box mounted on a tubing or casing.

The rod misalignment accommodating device provides for substantially improved aligning the polished rod with a stuffing box of an oil field pumping unit immediately abo e the christmas tree and just below an articulated horse's head of the pumping unit. Continuous pumping of oil wells to supply increased demand for crude oil is now permitted by government regulations and the present invention provides means to substantially reduce down time which is not only costly but takes a pumping unit out of service when it could otherwise be pumping crude oil for storage.

A long standing problem in pumping oil is the misalignment of rods in and through the stuffing box. Mis alignment is caused primarily because foundations which support pump jacks settle due to operation of the pump jack with the resulting misalignment of the horses head relative to a vertical line through the top of the pumping unit. Misalignment is greater and more critical as the height of the horse's head above the tubing or casing increases. Misalignmcnt of the rod over the stuffing box causes the rod to bind in the packing used to seal the top of the christmas tree and causes excessive wear of the polished rod, the packing, and the jam nut.

The principle objects of the present invention are: to provide a rod misalignment accommodating device particularly adapted to overcome the above mentioned problems; to provide such a rod misalignment accommodating device adapted to accommodate misalignment of an oil well rod with the longitudinal axis of a christmas tree through which the rod extends and thereby substantially reducing wear of bearings and seals and packing glands and wear of the oil well rod; to provide such a rod misalignment accommodating device permitting the rod to align itself in such a manner that the rod will go more perfectly through the stuffing box chamber on the christmas tree and thereby eliminate or substantially reduce the wear and frequent down time now experienced; to provide such a rod misalignment accommodating device having means communicating with a bore of a rod guide member having an oil well rod moveable therethrough for generating a signal in response to fluid pressure in the bore above a selected level; to provide such a rod misalignment accommodating device having means communicating with a chamber in a liquid receiving member having the oil well rod moveable therethrough for generating a signal in response to increased pressure due to presence of liquid flowing into the chamber from the bore in the guide member thereby indicating a need to replace packing or seal members on the guide member; and to provide such a rod misalignment accommodating device which is economical to manufacture. durable in construction. positive in operation. and particularly well adapted for the proposed use.

Other objects and advantages of this invention will become apparent in the following description which is taken in connection with the accompanying drawings wherein are set forth. by way of illustration and example, certain embodiments of this invention.

The drawings constitute a part of this specification and include an exemplary embodiment of the present invention and illustrate various objects and features of the oil well rod misalignment accommodating device.

FIG. 1 is a side elevational view of a pumping well having a rod misalignment accommodating device embodying features of the present invention mounted on an oil well christmas tree.

FlG. 2 is an enlarged longitudinal sectional view through the rod misalignment accommodating device.

FIG. 3 is an enlarged transverse sectional view taken on line 33, FIG. 2 and showing means for limited universal movement of a rod guide member in a body member.

FIG. 4 is an enlarged longitudinal sectional view through a modified rod misalignment accommodating device and showing leak detecting members.

FIG. 5 is an enlarged transverse sectional view taken on line 55. FIG. 4, and showing leak detecting means.

Referring more in detail to the drawings:

As required, detailed embodiments of the present invention are disclosed herein, however. it is to be understood that the disclosed embodiments are merely exemplary of the invention which may be embodied in various forms. Therefore. specific structural and functional details disclosed herein are not to be interpreted as limiting but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure.

In the disclosed embodiment of the present invention. the reference numeral 1 generally designates a self aligning stuffing box or device for accommodating misalignment of a rod 2 connected to the upper end of a string of sucker rods and an oil well tubing or casing 3. The rod misalignment accommodating device I includes a rod guide member 4 having a spherical portion 5 received in a spherical cavity 6 of a body member 7 mounted on the tubing or casing 3 and in the illustrated structure, the device 1 is mounted on an oil well christmas tree 8. The oil well polished rod 2 extends through a bore 9 in the rod guide member 4 and is slidably received in a floating bushing or closure member 10 mounted in a recess 1] in the body member 7 and the polished rod 2 is slidingly and sealingly received in pri mary seal members 12 mounted on the rod guide member 4. Pressure sensitive members 14 communicate with the bore 9 in the rod guide member 4 and generate a signal in response to fluid pressure in the bore 9 above a selected level. Liquid detecting members 15 communicate with a chamber 16 in a liquid receiving member 17 mounted on the rod guide member 4 and generate a signal in response to a pressure increase due to liquid flowing into the chamber 16 from the bore 9 in the rod guide member 4 and through the primary seal members 12 mounted on the rod guide members 4 thereby indicating the need for repair or replacement of the primary seal members 12.

FlG. 1 illustrates a typical pumping well using the polished rod 2 extending through the christmas tree 8 and into an oil well tubing or casing 3 and connected to a string of sucker rods in the tubing or casing 3. The pumping unit is mounted on a foundation 18 which in the usual case was installed by unskilled workmen wherein the foundation 18 is a concrete pad placed on existing soil [9 which was in its original condition. A gradual shift and settling of the foundation 18 upon uncompacted soil 19 generally occurs over a period of years particularly when there is water or liquid draining toward the foundation ]8 from adjacent structures or equipment thereby causing soft areas under a portion of the foundation 18.

A suitable gear reduction unit is mounted on the foundation l8 and is driven by a suitable motor (not shown). The gear reduction unit 20 is operative to effect movement of a walking beam 21. as later described, by means of an articulated throw or arms which push and pull. In the illustrated pumping unit. an arm 22 has one end suitably mounted on a drive shaft (not shown) of the gear reduction unit 20 and the other end pivotally connected to one end ofa pitman arm 23 which has the other end thereof pivotally connected to one end of the walking beam 21.

The walking beam 21 is pivotally mounted on a tower 24 and the vertically axis of the tower 24 is preferably parallel with the vertical axis of the tubing or casing 3, however. particularly for taller towers, such as 25 to feet above the foundation 18, it has been found that vibration of the foundation 18 causes compaction under the drive motor and gear reduction unit 20 with a corresponding shift in the top of the tower 24. This misalignment of the top of the tower 24 is proportional to the height of the tower 24 and such misalignment requires costly reworking of the well head.

A horses head 25 is mounted on the other end of the walking beam 21 and, in the illustrated unit, has a suitable cable 26 connected thereto, with the other end of the cable 26 being connected to an upper end of the oil well polished rod 2. The oil well christmas tree 8 is mounted on the top of the tubing or casing 3 and receives the polished rod 2. Misalignment of the polished rod 2 with the longitudinal axis of the christmas tree 8 and the tubing or casing 3 results in wear of the polished rod 2 and wear of seals or packing and packing glands within the entrance to the christmas tree 8 and a jam nut and a bushing (not shown) in conjunction with a sealing device on the upper end or entrance to the christmas tree 8.

Counter weights 21' are mounted on the walking beam 21 and positioned between the pitman arm 23 and the tower 24. The counter weights 21' are adjustable in position along the walking beam 21 to balance the weight of the horses head and the string of sucker rods used in the particular oil well.

FIGS. 2 and 3 illustrate the misalignment accommodating device 1 of the present invention which is mounted on the upper end or entrance of the christmas tree 8 and is operative to accommodate substantial misalignment between the polished rod 2 and the longitudinal axis of the christmas tree 8. The illustrated body member 7 has a side wall 27 having an interior surface defining the cavity 6. The illustrated recess ll is formed in a tubular extension or portion 28 extending from the side wall 27 of the body member 7 and the tubular extension or portion 28 has a side wall 29 defining a generally cylindrical extension of the body member 7 which is closed by an end wall 30 having a bore 31 therethrough and the bore 31 communicates with the recess 11 and the cavity 6 in the body member 7. The side wall 29 of the extension 28 is illustrated as having threads on the exterior surface thereof whereby the body member 7 is adapted to be mounted on the upper end of the christmas tree 8. The side wall 29 of the tubular portion 28 has an enlarged portion 32 (ill thereby defining a shoulder 33. for a purpose later described.

The floating bushing or closure member [0 is mounted in the recess ll and slidingly receives the polished rod 2 and is illustrated as a generally tubular member having one end thereof in engagement with the end wall 30 of the tubular portion 28. The floating bushing or closure member N) has a side wall 34 defining a generally cylindrical portion having an exterior diameter which is less than an interior diameter of the side wall 29 and the enlarged portion 32 thereof to thereby define a space between the side wall 34 and the enlarged portion 32 of the side wall 29 which will accommodate floating or lateral movement of the polished rod 2 relative to the bore 3! in the end wall 30 of the tubular portion 28. The floating bushing or closure member [0 may be formed of any suitable material which is dissimilar to the polished rod 2. such as brass. bronze, or any of the resin impregnated linen type materials, such as phenolic impregnated linen.

The interior diameter of the side wall 34 is less than the diameter of the bore 31 in the end wall 30 to thereby permit lateral movement of the polished rod 2 without engagement of the polished rod 2 with the surfaces defining the bore 3! in the end wall 30 of the tubular portion 28. The closure member or floating bushing 10 has a flange 35 on the other end thereof and the flange 35 is adapted to seat on the shoulder 33 and has a peripheral surface having a diameter less than the diameter of the interior of the side wall 29 thereby allow ing floating or lateral movement of the polished rod 2 relative to the rod guide member 4 and the surface defining the bore 9 therethrough.

The illustrated rod guide member 4 has the spherical portion 5 on one end thereof and adapted to be received in the cavity 6 and in engagement with the flange 35 of the floating bushing or closure member 10. The rod guide member 4 includes a guide extension 36 having a side wall defining a generally cylindrical elongated tubular portion extending from the spherical portion 5 and defining the bore 9 therethrough, which also extends through the spherical portion 5 and has a diameter larger than the polished rod 2 to thereby avoid contact between the polished rod 2 and the rod guide member 4.

The side wall of the guide extension 36 has a shoulder 38 formed in the interior surface thereof and the shoulder 38 is adapted to receive the primary seal members 12, as later described. The end of the guide extension 36 has threads on the exterior thereof. for a purpose later described.

The body member 7 has a retainer 39 suitably mounted on the upper end of the side wall 27 of the body member 7. as by cooperating threads, and has a first wall portion 40 having a surface engaging the spherical portion 5 of the rod guide member 4 for retaining the rod guide member 4 in the cavity 6 in the body member 7. The illustrated retainer 39 has a second wall portion 4] extending from the first wall portion 40 and spaced from the exterior of the side wall forming the guide extension 36 and defining a generally cylindrical recess having a diameter greater than the exterior diameter of the guide extension 36 to thereby permit universal movement of the rod guide member 4 in the cavity 6 in the body member 7.

Surfaces of the spherical portion 5 which are in engagement with the side wall 27 of the body member 7 and with the first wall portion 40 of the retainer 39 are preferably sealed to prevent escape of fluid, therefore. a first pair of spaced seal members 42 and 43 are mounted in suitable recesses in the surface of the spherical portion 5 and sealingly engage the surface of the first wall portion 40 of the retainer 39 and a second pair of spaced seal members 44 and 45 are mounted in suitable recesses in the surface of the spherical portion 5 and sealingly engage the side wall 27 of the body member 7.

The primary seal members 12 are mounted on the upper end of the guide extension 36 of the rod guide member 4 to prevent escape of fluid through the misalignment accommodating device 1 from the christmas tree 8. The illustrated primary seal members l2 include an annular bearing gland 46 having one end in engagement with and supported on the shoulder 38. The bearing gland 46 has a bore 47 adapted to slidingly engage the oil well polished rod 2 during reciprocable movement thereof. The bearing gland 46 is preferably split on a vertical axis for ease of installation and tits securely around the polished rod 2 to prevent the polished rod 2 from rubbing against the rod guide member 4. Phenolic impregnated linen has been found to be a suitable material for the bearing gland 46.

Suitable packing 48 is positioned in engagement with the other end of the bearing gland 46 and will be compressed against the polished rod 2. The packing members 48 are preferably split on a forty-five degree (45) angle when the packing is used in its horizontal position in the misalignment accommodating device 1 with the splits to be installed every 90.

A pack cap 49 is mounted on the end of the guide extension 36 and has an end wall 50 having a threaded outer ring 51 engaging the side wall of the guide extension or tubular portion 36. The end wall 50 of the packing cap 49 is in engagement with one end of an annular inner pressure bushing or ring 52 which is adapted to be received within the guide extension 36 and the ring 52 has the other end thereof in engagement with the packing 48 to retain same between the inner pressure bushing or ring 52 and the bearing gland 46. The end wall 50 of the packing cap 49 has a bore 53 therethrough adapted to slidingly receive the polished rod 2.

The annular inner pressure bushing or ring 52 is substantially similar to the bearing gland 46 and is preferably of a longitudinal dimension which will cooperate with the packing 48 and the bearing gland 46 to form a selected stack height particularly for molded seals which float in a sealing chamber while cut packing members require pressure applied thereto as by moving the pack cap 49 along the guide extension 36 toward the shoulder 38.

The pack cap 49 has a recess in the end wall 50 adapted to receive a suitable wiper in engagement with the periphery of the polished rod 2 and which will skim off or remove dirt. tar, snow. ice and other materials which could enter the primary seal members 12 and damage same.

When the oil well pump unit operates without on site observation. fluid pressure above a selected level in the bore 9 of the rod guide member 4 and the guide exten sion 36 generates a signal to a suitable computer or control system which may turn off the drive motor for the walking beam 21 thereby stopping pumping operations. In the illustrated structure, a recess 54 is formed in the interior surface of the side wall of the guide extension or tubular portion 36 and adapted to receive the pressure members 14 which include a pressure transmitter 55 having suitable points or contacts adapted to be closed in response to pressure build-up of fluid escaping from the christmas tree 8. Closing the contacts or points of the pressure transmitter 55 closes a circuit which generates a signal by means of a conductor 56 electrically connected to a suitable computer (not shown). The conductor 56 is suitably connected to the pressure transmitter 55 as by a cannon plug 57 which permits quick disconnect of the conductor 56 for service of the misalignment accommodating device 1.

FIGS. 4 and 5 illustrate the fluid detecting members 15 which are mounted on the end ofthe tubular portion or guide extension 36 and are adapted to detect presence of and generate a signal in response to an increase in pressure due to liquid flowing into the fluid detecting members 15 from the bore 9 of the rod guide member 4, such as due to wear of the bearing gland 46. packing 48, or annular inner pressure bushing or ring 52. In the illustrated embodiment, the pack cap 49 is replaced by the fluid receiving member 17 which includes a housing having a side wall 59 surrounding the oil well polished rod 2 and opposite end walls 60 and 61 thereby defining the chamber 16 surrounding the oil well polished rod 2 during reciprocable movement thereof. The illustrated fluid receiving member or housing 17 has a threaded outer ring 62 in engagement with the threaded end of the guide extension 36. The end wall 60 of the housing 17 is in engagement with one end of the annular inner pressure bushing or ring 52. The end wall 60 has a bore 63 therethrough adapted to slidingly receive the polished rod 2.

In the illustrated structure, liquid flowing into the chamber 16 closes suitable points or contacts of a transmitter 64 to complete a circuit and generate a signal to a computer (not shown) or other suitable control system for indicating an increase in pressure due to the presence of liquid in the chamber 16 above a predetermined pressure. The transmitter 64 is electrically connected to the control system (not shown) by a conductor 65 which is suitably removably connected to the transmitter 64 as by a suitable cannon plug 66 or the like thereby permitting quick removal of the conductor 65 from the transmitter 64 during service of the misalignment accommodating device 1. A suitable drain cock 67 is positioned adjacent the end wall 60 and is adapted to bleed out any accumulating of oil or other liquid in the chamber 16 after the packing 48 has been repaired or replaced. The transmitter 64 should be removed and cleaned to permit restarting the sensing cycle.

While the transmitters 55 and 64 have been illustrated as electro chemical contact points, it is to be understood that a sensitive potentiometer could be used to indicate the presence of liquid in the bore 9 or chamber 16 above a predetermined pressure.

The chamber 16 may have a suitable lubricant therein to provide protection for the polished rod 2 and the seals or packing 48. The lubricant in the chamber 16 is not under pressure. therefore, the fluid detecting members 15 will sense and indicate any pressure increase in the chamber 16 due to a failure of the primary seal or packing as defined by the seal members 12.

When the chamber 16 has suitable lubrication material therein. the drain cock 67 may be replaced by a suitable grease zcrk, which would allow the lubricant to enter the chamber 16 and retain same therein until pressure in the chamber exceeds a predetermined level.

When a pressure sensitive potentiometer is used with the fluid detecting members 15 to detect pressure increase in the chamber 16. it is not necessary to drain the chamber 16, however, pressure therein must be relieved in any suitable manner. such as the drain cock 67 or a suitable grease zerk. It is also not necessary to clean the chamber 16 each time the pressure exceeds the predetermined level when the pressure sensitive potentiometer is used with the fluid detecting members 15.

Packing or seal, members 68 are mounted in engagement with the end of the side wall 59 and include a pack cap 69 constructed substantially similar to the pack cap 49. The pack cap 69 is in engagement with an annular inner pressure bushing or ring 52 which engages suitable packing 70 positioned between the end wall 61 and the ring 527 to thereby prevent escape of liquid from the chamber 16.

During pumping operations. a signal from the pressure transmitter 55 or the transmitter 64 activates suitable controls to discontinue operation of the pumping unit. The misalignment accommodating device 1 is disassembled and the floating bushing or closure member 10, bearing gland 46, packing 48, and pressure ring 52 are examined to determine if replacement is necessary. The transmitters 55 and 64 are cleaned and reinstalled and the conductors 56 and 65 respectively are connected. The polished rod 2 is also examined to locate points or areas of wear which would prevent an effective seal between the rod 2 and the packing in engagement therewith.

The polished rod 2 is coaxial with the pack cap 49, packing 48, and bearing gland 46 or coaxial with the pack cap 69, packing 70, packing 48. and bearing gland 46. Misalignment of the polished rod 2 with the christmas tree 8 is accommodated by limited universal movement of the spherical portion 5 in the cavity 6 in the body member 7 and movement of the polished rod 2 and floating bushing or closure member 10 laterally in the recess 11 of the tubular portion 28 of the body member 7.

It is to be understood that while I have illustrated and described certain forms of my invention, it is not to be limited to the specific forms or arrangement of parts herein described and shown.

What I claim and desire to secure by Letters Patent 1. A self aligning well head structure for use with an oil well tubing and a pumping unit reciprocating a polished rod extending into the well tubing and connected to a string of sucker rods, said self aligning well head structure comprising:

a. a body member having walls defining a cavity adapted to receive a portion of a sphere;

b. a tubular portion extending from said body member and having a side wall and an end wall with a bore therethrough, said tubular portion having a recess coaxial with said bore and communicating with the cavity in said body member, said tubular portion of said body member being adapted to be mounted on an oil well christmas tree;

c. a tubular bushing member having opposite ends and positioned in said tubular portion of said body member and having one end thereof in engagement with the end wall of said tubular portion and a side wall defining a bore adapted to slidingly receive an oil well polished rod during reciprocable movement thereof, said tubular bushing member being smaller than said recess for limited lateral movement of said bushing member and oil well polished rod;

d. a rod guide member having a generally spherical end portion received in the cavity in said body member and an elongated tubular portion extending from the spherical end portion and having a side wall defining a bore therethrough, said spherical end portion engaging the other end of said bushing member and having a bore therethrough communicating with and coaxial with the bore through the tubular portion of said rod guide member, said bores through the tubular portion of the body member and through the spherical end portion and tubular portion of the rod guide member being larger than the polished rod providing a clearance greater than the limited lateral movement of said bushing member and polished rod;

e. a retainer mounted on said body member and having walls engaging said spherical end portion of said rod guide member for retaining same in the cavity in said body member; and

. seal means mounted on said tubular portion of said rod guide member and adapted to slidingly and sealingly engage the oil well polished rod during reciprocable movement thereof.

2. A self aligning well head structure as set forth in claim 1 including:

a. tubular means mounted on said tubular portion of said rod guide member and engaging said seal means for defining a chamber surrounding the oil well polished rod during reciprocable movement thereof;

b. means communicating with the chamber for detecting presence of and generating a signal in response to liquid flowing into the chamber from the bore of said rod guide member; and

c. second seal means mounted on said means defining the chamber and spaced from said first named seal means and adapted to slidingly and sealingly engage the oil well polished rod during reciprocable movement thereof while sealing the chamber;

d. said first named seal means and said second seal means being above the spherical end portion and said bushing member being below said spherical end portion with said first named seal means, second seal means and bushing member providing sliding engagement with and guiding of said polished rod.

3. A self aligning well head structure as set forth in claim 2 including:

a. means on the side wall of said tubular portion of said rod guide member defining a recess therein below said first named seal means; and

b. means communicating with the recess in the side wall of said tubular portion of said rod guide member for generating a signal in response to fluid pressure above a selected level.

4. A self aligning well head structure as set forth in claim 1 wherein:

a. said recess in said tubular portion of said body member is enlarged to define a shoulder adjacent to and spaced from the cavity in said body member;

b. said bushing member has a flange in engagement with said shoulder;

c. said spherical end portion of said rod guide memher is in engagement with the flange on said bushing member; and

d. said bushing member and said recess in said tubular portion of said body member having relative sizes to accommodate limited lateral movement of the oil well polished rod and retain same from engaging surfaces of the bores in the body member and rod guide member whereby the polish rod has sliding engagement and guiding support with the bushing member and seal means.

5. A misalignment accommodating device for oil well pump heads and comprising:

a. a body member having walls defining a cavity adapted to receive a portion of a sphere;

bl walls extending from said body member and defining a recess communicating with the cavity, one of said recess defining walls having a bore therethrough and communicating with the recess;

c. a bushing member in the recess and having a bore adapted to slidingly receive an oil well polished rod during reciprocable movement thereof, said bushing being smaller than said recess for limited lateral movement of the bushing member and polished rod;

d. a rod guide member having a generally spherical portion received in the cavity in said body member and having a bore therethrough alignable with the bore through said bushing member and said recess defining walls; and

e. seal means mounted on said rod guide member and adapted to slidingly and sealingly engage the oil well polished rod during reciprocable movement thereof;

f. said bores in said one recess defining wall and said rod guide member being larger than the polished rod and providing a clearance greater than the limited lateral movement of the bushing member, said bushing member and seal means providing sliding engagement and guiding support for said polished rod. 

1. A self aligning well head structure for use with an oil well tubing and a pumping unit reciprocating a polished rod extending into the well tubing and connected to a string of sucker rods, said self aligning well head structure comprising: a. a body member having walls defining a cavity adapted to receive a portion of a sphere; b. a tubular portion extending from said body member and having a side wall and an end wall with a bore therethrough, said tubular portion having a recess coaxial with said bore and communicating with the cavity in said body member, said tubular portion of said body member being adapted to be mounted on an oil well christmas tree; c. a tubular bushing member having opposite ends and positioned in said tubular portion of said body member and having one end thereof in engagement with the end wall of said tubular portion and a side wall defining a bore adapted to slidingly receive an oil well polished rod during reciprocable movement thereof, said tubular bushing member being smaller than said recess for limited lateral movement of said bushing member and oil well polished rod; d. a rod guide member having a generally spherical end portion received in the cavity in said body member and an elongated tubular portion extending from the spherical end portion and having a side wall defining a bore therethrough, said spherical end portion engaging the other end of said bushing member and having a bore therethrough communicating with and coaxial with the bore through the tubular portion of said rod guide member, said bores through the tubular portion of the body member and through the spherical end portion and tubular portion of the rod guide member being larger than the polished rod providing a clearance greater than the limited lateral movement of said bushing member and polished rod; e. a retainer mounted on said body member and having walls engaging said spherical end portion of said rod guide member for retaining same in the cavity in said body member; and f. seal means mounted on said tubular portion of said rod guide member and adapted to slidingly and sealingly engage the oil well polished rod during reciprocable movement thereof.
 1. A self aligning well head structure for use with an oil well tubing and a pumping unit reciprocating a polished rod extending into the well tubing and connected to a string of sucker rods, said self aligning well head structure comprising: a. a body member having walls defining a cavity adapted to receive a portion of a sphere; b. a tubular portion extending from said body member and having a side wall and an end wall with a bore therethrough, said tubular portion having a recess coaxial with said bore and communicating with the cavity in said body member, said tubular portion of said body member being adapted to be mounted on an oil well christmas tree; c. a tubular bushing member having opposite ends and positioned in said tubular portion of said body member and having one end thereof in engagement with the end wall of said tubular portion and a side wall defining a bore adapted to slidingly receive an oil well polished rod during reciprocable movement thereof, said tubular bushing member being smaller than said recess for limited lateral movement of said bushing member and oil well polished rod; d. a rod guide member having a generally spherical end portion received in the cavity in said body member and an elongated tubular portion extending from the spherical end portion and having a side wall defining a bore therethrough, said spherical end portion engaging the other end of said bushing member and having a bore therethrough communicating with and coaxial with the bore through the tubular portion of said rod guide member, said bores through the tubular portion of the body member and through the spherical end portion and tubular portion of the rod guide member being larger than the polished rod providing a clearance greater than the limited lateral movement of said bushing member and polished rod; e. a retainer mounted on said body member and having walls engaging said spherical end portion of said rod guide member for retaining same in the cavity in said body member; and f. seal means mounted on said tubular portion of said rod guide member and adapted to slidingly and sealingly engage the oil well polished rod during reciprocable movement thereof.
 2. A self aligning well head structure as set forth in claim 1 including: a. tubular means mounted on said tubular portion of said rod guide member and engaging said seal means for defining a chamber surrounding the oil well polished rod during reciprocable movement thereof; b. means communicating with the chamber for detecting presence of and generating a signal in response to liquid flowing into the chamber from the bore of said rod guide member; and c. second seal means mounted on said means defining the chamber and spaced from said first named seal means and adapted to slidingly and sealingly engage the oil well polished rod during reciprocable movement thereof while sealing the chamber; d. said first named seal means and said second seal means being above the spherical end portion and said bushing member being below said spherical end portion with said first named seal means, second seal means and bushing member providing sliding engagement with and guiding of said polished rod.
 3. A self aligning well head structure as set forth in claim 2 including: a. means on the side wall of said tubular portion of said rod guide member defining a recess theRein below said first named seal means; and b. means communicating with the recess in the side wall of said tubular portion of said rod guide member for generating a signal in response to fluid pressure above a selected level.
 4. A self aligning well head structure as set forth in claim 1 wherein: a. said recess in said tubular portion of said body member is enlarged to define a shoulder adjacent to and spaced from the cavity in said body member; b. said bushing member has a flange in engagement with said shoulder; c. said spherical end portion of said rod guide member is in engagement with the flange on said bushing member; and d. said bushing member and said recess in said tubular portion of said body member having relative sizes to accommodate limited lateral movement of the oil well polished rod and retain same from engaging surfaces of the bores in the body member and rod guide member whereby the polish rod has sliding engagement and guiding support with the bushing member and seal means. 